The present invention is directed to a reusable impact energy absorbing or dissipating device and more specifically to a device having a shock absorber incorporated therein comprised of a piston and a cylinder assembly filled with a liquid and provided with at least one relief valve extending through the side wall of the cylinder whereby the liquid within the cylinder will be discharged through the valve upon the application of impact pressure on the piston. The discharged fluid can additionally pass through restricted passages to dissipate energy. A balloon is connected to the top and bottom of the cylinder in a sealed manner to capture the fluid expelled from the piston through the valve. The entire piston and cylinder assembly and the balloon are further disposed within a rigid container to protect the balloon from accidental puncture. Upon removal of the impact pressure on the piston, a spring within the cylinder will return the piston to its original position thereby creating a vacuum within the cylinder. Due to the presence of the vacuum and the elastic pressure of the balloon on the liquid, the liquid will return through the valve into the cylinder whereby the system may be reused.
An energy absorbing device suitable for use with a bumper or any other impact device is disclosed in applicants previous U.S. Pat. No. 6,148,970. The device is comprised of a piston traveling within a liquid filled chamber which has a plurality of weak spots of varying thickness formed in sequence along the length of the side wall of the cylinder. A first weak spot closest to the impact receiving end of the device is the weakest of all the spots and subsequent weak spots gradually increase in strength. Upon the application of a force to the piston the liquid pressure will cause the first weak spot to rupture. If the force applied to the piston is sufficiently large, subsequent weak spots will rupture in sequence to provide a superior shock absorption mechanism. However once the weak spots have ruptured it is necessary to replace the cylinder which can be time consuming and expensive.
Other types of shock absorbing systems involving the use of shear pins, deformable tube and blowout ports for a fluid and the like are disclosed in U.S. Pat. Nos. 4,823,923, 4,641,872, 4,190,276, 4,257,581, and 3,200,584. However each of these impact dissipating devices damaged the various components to the extent that the entire system must be replaced or repaired.
U.S. Pat. No. 3,844,544 to Keilholz discloses a hydraulic shock absorber in which a damping fluid is displaced from a flexible impact receiving container through a fluid passage into a storage chamber for the damping fluid. A separating piston is provided for separating damping fluid entering the storage chamber from a compressible gas within the storage chamber. A flow control means is disposed in the fluid passage and is moveable with the separating piston for progressively reducing the rate of passage of the damping fluid into the storage chamber as the piston is moved by the damping fluid into the storage chamber whereby substantial constant damping effect results in the course of the impact receiving container receiving an impact.
U.S. Pat. No. 5,370,429 to Reuber et al. is directed to a bumper system for a vehicle. An extendable bumper is resiliently disposed in the direction of impact. The bumper system includes a cylinder, a piston disposed in the cylinder, a piston rod connected to the bumper on one end and to the piston on the opposite end, a damping fluid in cylinder contacting the piston for damping movement of the bumper, a valve, an equilibrium chamber having said damping fluid and communicating with the cylinder through the valve and a cylindrical pin having a groove, said cylindrical pins being screwed to the piston rod on one end of the piston rod opposite the piston and are guided in the equilibrium chamber. The groove is formed parallel to the piston rod and is tapered toward the bumper so that the size of the groove decreases as the bumper is retracted and connecting the cylinder with the equilibrium chamber. Thus the damping effect of the mounting means on the bumper depends upon the position of the bumper.
The present invention is directed to a reusable impact energy absorbing device associated with a bumper. The energy absorbing device is comprised of a cylinder having a piston moveable therein with a piston rod adapted to be connected to the bumper. Spring means are provided within the cylinder in contact with the piston. The cylinder is filled with a suitable fluid and one or more valves are provided in the side wall of the cylinder to absorb the energy. Upon receiving an impact the piston is moved into the cylinder to displace the fluid through the valve means directly into a chamber defined by a flexible elastic balloon having a vacuum therein or indirectly through restricted passages. Subsequent to the impact the spring within the cylinder will move the piston outwardly thereby creating a partial vacuum within the cylinder. The vacuum in combination with the pressure exerted on the fluid by the balloon will return the fluid to the cylinder through the valve.
In lieu of a piston rod connected to the bumper, the present invention also contemplates the use of a flexible bag filled with fluid which would be located in the vicinity of the bumper or within a door panel so that upon impact the flexible bag would be distorted to force the fluid out of the bag to a conduit into the cylinder having the piston movable therein.
The foregoing objects features and advantages of the invention will be set forth in the following description of the invention in conjunction with the drawings.